blowing smoke when letting off gas,and slowing down from highway speeds

[dodge360blowing smoke]

Hi folks
i am the new to me owner of a  1980 dodge empress 2300,made by skylark recreational vehicle Ltd,from Alberta Canada.the m/h has 73000 km's,my issue is with the engine.It starts fine,warms up easily and off i go down the highway,NOW comes the smoke(white)but only when i let off the gas,and when slowing down to make a turn it gets really thick,i have changed the thermostat,plugs looked oily so i just cleaned the up(one was really bad)i will be putting in new plugs.rad fluid is not "brown milkshake colour),oil looks good,so i am hoping it not a blown head gasket,because i figure a blown gasket would be blowing smoke all the time.I have found on the net different PROBABLE causes,one is a tranny modulator valve,dead cylinder,head gasket,vacuum issues,pvc valve,egr valve.So if anyone has had similar issues and did you find a solution i sure would love some input from a kindred soul .


Thanks
i??

[legomybago]

Cracked pistons.....

[Elandan2]

The Dodge transmission doesn't have a modulator valve so there is one item off your list!! I would be leaning toward valve guides and seals allowing oil past and into the combustion chamber under high vacuum conditions, such as letting off on the gas.  Rick

[dodge360blowing smoke]

I have heard about valve guides and such causing this problem,i have been using "sea foam" engine and fuel treatments to try and get them working,but no luck yet,do i have to pull the engine and overhaul it?

[legomybago]

Bad oily plugs is not a good thing...You could do a compression check, see if any holes are obviously out of speck...but even if you have good numbers all the way around, you could still have piston issues...Your more than likely going to be pulling the heads...Are you sure that rig doesnt have 173K?? You'd be surprised how many people try and play the "low mile 5 digit odometer game" W%

[pvoth1111]

Sorry its broken.

[Froggy1936]

Check compression If all are good and fairly even The problem is valve seals Especially on intake valves The possibility of bad pistons is miniscule and bad rings are not likely unless engine was run overheated for a long time . The seals can be replaced without pulling the cly heads useing compressed air thru spark plug hole Requires makeing a plug with an air fitting . and revolveing engine to closed valves on cly haveing springs removed This operation require some experience with engines  ! Frank

[dodge360blowing smoke]

thanks so much for that idea ,i will go that route if compression test is good,i am a retired airforce mech so the engine work wont be a issue,i am waiting to get a manual and i am just doing things as best as i can right now.will change to new plugs tomorrow ,start her up and see if anything changes or i get a new indication of something else  D:oH!

[Mr. T]

My wife saw your description and said that perfectly describes me in a busy grocery store on Sunday afternoon.  Says my piston ain't working so good either.

Any how, good luck on your cylinder rebuild.  I wouldn't take any short cuts.

Don T.

[TerryH]

I go along with Froggy.
Deceleration, especially downhill does not necessarily decrease RPM, but it does increase vacuum, pulling unwanted oil into the cylinders, past the intake valves/guides. It has to burn and then exhaust as smoke. Additional heat creates a "condensation burn" as well.
A test, provided you are willing to drive it as is, is to go down a hill, foot off gas, and hit the gas at the bottom of the hill. Be watching your mirror or have a passenger watching. Color and amount of smoke and when it stops will indicate a possible problem.
Anyway, I agree with valve seals at this point.

My opinion only.

Terry

[liquidwrench63]

white is usually coolant or tranny fluid, blue is oil and black fuel correct me if im wrong

[legomybago]

If the valve guide seals were that bad, it would smoke on intitial cold start-up, (he says it doesnt). I think the motor is worn out...Only reason I say that, is I've had the exact same symtoms on a high mile motorhome 1983, with a 454. Ran great, didnt miss, didnt smoke, just looked like James Bond when decelerating (white smoke), you couldnt see traffic behind you. It had 3 cracked worn out pistons. Why that happened? I dont know? Hopefully it's not that with this Dodge, but that was my experience with his symtoms as he explained...

He will probably fix it with a, "found a loose vacuum line, and plugged it"...All good now!    lol

[Rickf1985]

I have seen this many times on older engines. (in older times W% ) The oil rings are most likely worn. With that scenario you would get a good compression test and even a good leakdown test as long as the top two rings are good. On engines that are only run very seldom the oil rings take a lot of abuse due to dry cylinder walls and the occasional rusty cylinder. They are very thin so they do not hold up as long as compression rings under those conditions.

[dodge360blowing smoke]

well after the new plugs installed,started up better,sounded better,so off i went for a road test,still smoking.Did a compression test and #5 cylinder cannot get above 50 psi,all the rest were over 120,so it looks like a engine job over the winter for me     


   

[dodge360blowing smoke]

After talking it over with my banker(loving wife),we are looking for a new engine for our m/h ,what are some choices that I could use.Do I rebuild the old one or get a new/refurbished,and should I also do the tranny as well.Are there newer engines that will offer power and better mph that bolts to the tranny?

So many questions to get figured out

HELP PLEASE... And thanks

[LJ-TJ]

From a fellow Canadian all the way over here in Ontario. So, here's what I've learned from replacing a 318 in my 1975 Winnebago. Most if not all new rebuilt engines are not new. If the parts are within spec they are put back in the engine so your not really getting a new engine. Personally if it were me I'd try and find a good used 440. Should be able to pick one up for around $200.00 dollars. Then I'd find a small good machine shop with a good reputation and have them rebuild it for me which should cost around $1200.00 dollars. If your rig is like a 1975 Winnebago you can pull the engine out in half a day by yourself and put the new one back in in half a day. This is from a fellow who doesn't know one end of a wrench from another and finally ended up doing the swap himself with the help of all the chaps on this site.

[Rickf1985]

As far as the transmission goes, since you already have the engine out it is asy to get to so I would go for it. I am not that knowledgeable about the Dodge Winnies but 75 should be a 727 Torqueflite. They are as close to indestructible as it gets. Here is a good book to get and you can do it yourself.http://www.amazon.com/Torqueflite-A-727-Transmission-Handbook-HP1399/dp/1557883998 . Also be sure to put in a shift kit, not a race kit but a heavy duty kit. I prefer Trans-Go and iof you call them they will tell you what one to use. A race type kit shifts too hard for motorhome use. Also get a good plate type transmission cooler.

[dodge360blowing smoke]

Have put the word out to my friends ( they are truckers) to look for a 440 engine to put back in place of the 360 ,and I am  now looking for the best place to find info on a big job like this?

[Elandan2]

Just in case you didn't know, you will need a transmission that will bolt up to a 440, the small block Dodge engines use a transmission with a smaller bell housing.  Rick

[LJ-TJ]

You have found the best place. Here we are. The only dumb question ever asked here was the one that wasn't asked.

[legomybago]

Have your 360 rebuilt...I wouldnt mess with the tranny unless you already have issues with it...If you go 440, your going to have a lot of work ahead of you...exhaust, transmission bell housing change, etc, etc, etc....the 440 would be an upgrade..but...